The present invention relates to a method for producing layered multichannel metal plates containing dynodes for amplifying optical images or other two-dimensional signal patterns by means of secondary electron multiplication and to the use of multichannel plates produced according to this method.
It is known to amplify optical images or other two-dimensional signal patterns, or arrays, by means of so-called multichannel plates as described in Federal Republic of Germany Laid-Open Application DE-OS No. 3,150,257 and Federal Republic of Germany Patent DE-PS No. 2,414,658. Such plates are composed of a plurality of electrically mutually insulated metal layers provided with closely adjacent holes, with a plurality of these plates being stacked in such a manner that the holes form closely adjacent channels extending essentially perpendicularly to the major surfaces of the plate.
The layers are individually connected to a voltage source in such a manner that a step-wise potential gradient is created between them. Thus the channels perform the function of secondary electron multipliers, with the metal layers provided with the holes constituting the dynodes. The holes of the individual dynodes may be produced by chemically etching through illuminated and developed photo resist masks.
Good results are obtained in practice if the hole diameters and the thickness of the dynode are approximately the same. "Spektrum der Wissenschaft" [Science Spectrum], January 1982, pages 44-55, further indicates that in multichannel image amplifier plates made of glass the channels should be given a curvature or arranged to follow a zigzag pattern. In the latter case, a plurality of plates having channels which are oblique to the plate surfaces are stacked.
If, in stacked multichannel image amplifier plates, spatial resolution is to be as high as in image amplifier plates made of glass, the diameters of the holes and thus the thicknesses of the dynodes must be of the order of magnitude of 30 microns or less. This results in considerable problems in mutual alignment and electrical insulation of the separately produced foil-like dynodes.